The present invention relates to a polarized electrode for an electric double-layer condenser and an electric double-layer condenser manufactured by using the polarized electrode and, more particularly, to a polarized electrode for an electric double-layer condenser, which can suppress the damage or separation of an electrode contained in the polarized electrode.
Further, the present invention relates to a polarized electrode for an electric double-layer condenser, a process for manufacturing the same, and an electric double-layer condenser manufacturing by using the polarized electrode and, more particularly, to a polarized electrode for an electric double-layer condenser, in which two end portions of the electrode are protected.
Still further, the present invention relates to a process for manufacturing an electrode sheet for an electric double-layer condenser, in which sheet-shaped electrodes are adhered to the surfaces of a conductive foil through an conductive adhesive, and a laminating apparatus suitable for executing the manufacturing process.
The electric double-layer condenser is also called as the xe2x80x9celectric double-layer capacitorxe2x80x9d and is provided with a polarized electrode and an electrolyte for storing electric charges by using the electric double-layer formed in the boundary between the polarized electrode and the electrolyte. Therefore, the electric double-layer condenser has a high farad-level capacity and is excellent in the charging/discharging cycle characteristics for quick-charging operations so that it is applied in recent years to various fields for a backup power source of an electronic device or a car-mounted battery.
The electric double-layer condenser of the prior art will be described with reference to FIG. 5. FIG. 5 is a sectional diagram schematically showing a construction of an electric double-layer condenser 101 of one example of the prior art. This electric double-layer condenser 101 is constructed such that a pair of polarized electrodes having collecting foils 104 and 104 adhered to carbon electrodes 105 and 105 are arranged in a container 102 through a separator 103, and such that the container 102 is filled with an ion-conductive electrolyte.
When a voltage is applied to the electric double-layer condenser 101 of the prior art thus constructed, electric double layers, in which charges (as indicated by symbols + and xe2x88x92) are densely present at a distance as short as the molecular level, are formed at the interface between the solid polarized electrode (having the carbon electrodes 105 adhered to the collecting foils 104) and the liquid electrolyte, so that the charges are stored in that electric double layers.
Here, the electrolyte to be used in that electric double-layer condenser 101 is coarsely divided into the xe2x80x9caqueous electrolytexe2x80x9d prepared by adding an electrolyte to a dilute sulfuric acid and the xe2x80x9corganic solvent group electrolytexe2x80x9d prepared by adding an electrolyte to an organic solvent, which are properly used for the purpose. Specifically, the electric double-layer condenser using the aqueous electrolyte is relatively low in the internal resistance so that it is advantageous in the power density and relatively higher in the degree of freedom for setting the output voltage. On the other hand, the electric double-layer condenser using the organic solvent group electrolyte can have a relatively high electric strength per unit cell so that it is advantageous in the energy density and can use a relatively inexpensive and light metal foil of aluminum or the like.
(Polarized Electrode)
FIG. 3A and FIG. 3B are diagrams schematically showing practical examples of such electric double-layer condenser. FIG. 3A is an exploded perspective view of a laminated type electric double-layer condenser, and FIG. 3B is a sectional view of a coin type electric double-layer condenser. Specifically, the laminated type electric double-layer condenser 1 is constructed such that a wound member 3, which is prepared by spirally winding polarized electrodes 9 and 10 having electrodes 12 and 15(e) adhered to collecting foils 11 and 14 through separators 17 and 18, is housed in a container 2, and such that the container 2 is filled with the aforementioned electrolyte.
On the other hand, a coin type electric double-layer condenser 1xe2x80x2 shown in FIG. 3B is constructed such that a laminate, which is prepared by laminating polarized electrodes having electrodes 12xe2x80x2 and 15xe2x80x2 adhered to collecting foils 11xe2x80x2 and 14xe2x80x2 through a separator 17xe2x80x2, is housed in a container 2xe2x80x2, and such that the container 2xe2x80x2 is filled with the aforementioned electrolyte. In FIG. 3B, reference numeral 21 designates a portion to be filled with the electrolyte, and reference numeral 22 designates a packing provided for preventing the leakage of the electrolyte to the outside. The winding type electric double-layer condenser shown in FIG. 3A and the coin type electric double-layer condenser 1xe2x80x2 shown in FIG. 3B are suitable for a backup power source of an electronic device or a car-mounted battery.
In this electric double-layer condenser, the polarized electrodes have to be provided with a porous structure for satisfying various characteristics demanded in the fields of the backup power source of the electronic device or the car-mounted battery. The additional demands are the durability for suppressing the cracking or damage and the strength for holding the shape properly while supposing the continuous use in various modes and under various conditions for a long time, and the proper coordinations between the flexibility cost suited for the shaping works at the manufacturing time.
A polarized electrode for an electric double-layer condenser, as satisfying those demands, is constructed such that electrodes, which are prepared by dispersing an active substance including mainly active carbon and a conductive filler through a binder and by forming them into a sheet shape, are adhered through an adhesive layer.
However, the electric double-layer condenser having such polarized electrode has an inherent problem that the electrode material such as carbon contained in the electrode partially falls due to the aging to invite deteriorations in performance such as the drop in the output voltage or the rise in the internal resistance. If the electrode material thus having fallen is floating in the electrolyte or is mixed into the separator, moreover, the desired output voltage is difficult to be stably kept for a long time.
As the method for preventing the falling of electrode forming granules or one of the electrode materials of the electric double-layer condenser, therefore, there is disclosed a method (as referred to Patent Publication) for manufacturing a polarized electrode for an electric double-layer condenser, by forming an intimate mixture of a material of an electrode such as fine carbon powder (or active carbon), a conductive filler and a binder, and a liquid lubricant into a sheet shape, subsequently by removing the lubricant, sequentially by stretching the formed sheet uniaxially or multi-axially.
In order to solve the aforementioned problem, alternatively, there is disclosed an electric double-layer condenser (as referred to Patent Publication 2), in which the tensile strength of a polarized electrode is regulated to 0.13 MPa or higher so as to prevent the falling of the carbon including the aforementioned electrode into the electrolyte.
[Patent Publication 1]
JP-B-7-105316
[Patent Publication 2]
JP-A-2001-267187
However, the polarized electrode for the electric double-layer condenser of the prior art can eliminate the falling of the granules contained therein to some extent. On the other hand, there is left unsolved a problem that the end portion is more susceptible to damage than the remaining portion at the step of packing that polarized electrode. If the end portion of the collecting foil is damaged, more specifically, the end portion of the electrolyte adhered to the collecting foil is also so adversely affected that the self-discharge of the electric double-layer condenser increases or that the dispersion of the self-discharging percentage becomes large among the products of the electric double-layer condenser. However, this point is not especially considered in the aforementioned polarized electrode for the electric double-layer condenser of the prior art.
However, the polarized electrode for the electric double-layer condenser of the prior art can eliminate the falling of the granules contained therein to some extent. After this polarized electrode is manufactured, however, the electrode may be separated or may fall from the collecting foil at the step of packaging the polarized electrode. When the electrode thus separates or falls from the collecting foil, it is feared that the self-discharge of the electric double-layer condenser increases or that the dispersion of the self-discharging percentage becomes large among the products of the electric double-layer condenser.
Further, the electric double-layer condenser (or capacitor) has a high capacity and is excellent in the charging/discharging cycle characteristics so that it is investigated for applications to various devices such as various backup power sources for automobiles. As the electric double-layer condenser of a high capacity of this kind, there is a cylindrical type, which is constructed by winding a pair of positive and negative electrode sheets having carbon sheets (or polarized electrodes) including mainly active carbon and held on an aluminum foil (or a collecting electrode), in a coil shape through separators in between, and by housing the electrode sheets in a cylindrical case while being impregnated with an electrolyte.
In this case, the carbon sheets (or the sheet-shaped electrodes) and the aluminum foil (or the conductive foil) are adhered (or laminated) to each other with the conductive adhesive so that they may be integrated (as referred to Patent Publication 3). The reason for the use of the conductive adhesive is to reduce the contact resistance at the joint boundary between the sheet-shaped electrodes and the conductive foil. If the contact resistance between the sheet-shaped electrodes and the conductive foil is high, the internal resistance of the electric double-layer condenser is increased to invite a drop in the performance.
[Patent Publication 3]
JP-A-11-154630
Here, a continuous and long electrode sheet is required for manufacturing the aforementioned cylindrical type electric double-layer condenser of the high capacity. It is also desired to reduce the contact resistance at the joint boundary between the sheet-shaped electrodes and the conductive foil constructing that electrode sheet and to attain the sufficient joint strength between them. If the conductive adhesive layer to joint the sheet-shaped electrodes and the conductive foil is thick at this time, the internal resistance becomes high, and the thickness is increased as a whole to lower the filling density of the capacitor container. If the thickness becomes heterogeneous, on the other hand, the adhesion is not stabilized to fail to attain a sufficient joint strength.
The present invention is conceived to solve the aforementioned problems and has an object to provide a polarized electrode for an electric double-layer condenser, which has a structure for preventing the damage of the end portion of the electrolyte belonging to the collecting foil, in the process for manufacturing the electric double-layer condenser, and an electric double-layer condenser using the polarized electrode.
In order to solve the aforementioned problems, we have clarified that the end portion of the electrode adhered to the collecting foil is hardly susceptible to the damage, if the end portion of the electrolyte is arranged in the process for manufacturing the electric double-layer condenser at the portion not to obstruct the voltage keeping of the electric double-layer condenser and at a portion spaced within a predetermined range from the end portion of the collecting foil, as might otherwise be susceptible to the damage. As a result, we have created the invention by finding that the separation of the end face of the electrode and the falling of the active substance from the electrode are reduced to suppress the self-discharging percentage of the electric double-layer condenser at a low value and to reduce the dispersion of the self-discharging percentage.
(1) In order to solve the aforementioned problems, according to the invention, there is provided a polarized electrode for a laminated type electric double-layer condenser, in which a band-shaped electrode member including an electrode: prepared by dispersing an active substance including mainly active carbon and a conductive filler through a binder and by forming them into a sheet shape; and adhered to at least one face of a collecting foil having a conductivity, and a separator having a shape corresponding to that of the electrode member are alternately laminated and spirally wound up. The end portion of the electrode is spaced, at the two axial end portions of the laminated type polarized electrode, at a distance of 0.1% or more of the width of the electrode member from the end portion of the electrode member.
With this construction, the end portion of the electrode is spaced, at the two axial end portions of the laminated type polarized electrode, at a distance of 0.1% or more of the width of the electrode member from the end portion of the electrode member. Therefore, the direct damage of the electrode can be prevented, even if a stress to act on the end portion of the polarized electrode occurs at the step of winding the band-shaped polarized electrodes spirally through the dielectric separator having a shape corresponding to the polarized electrodes into the wound member and at the step of packaging the wound member. As a result, the separation of the end face of the electrode member and the falling of the active substance from the electrode member can be reduced to provide the polarized electrode for the laminated type electric double-layer condenser excellent in the voltage keeping characteristics.
Here in the invention, the aforementioned xe2x80x9cend-portion of the laminated type polarized electrodexe2x80x9d and the aforementioned xe2x80x9cend portion of the electrode memberxe2x80x9d imply the identical portions. Moreover, the aforementioned xe2x80x9cwidth of the electrode memberxe2x80x9d is identical to the xe2x80x9cwidth of the collecting foilxe2x80x9d.
(2) In the aforementioned polarized electrode for a laminated type electric double-layer condenser according to the invention, it is preferred that the end portion of the electrode is spaced, at the two axial end portions of the laminated type polarized electrode, at a distance of 0.1% to 10% of the width of the electrode member from the end portion of the electrode member.
With this construction, the capacity reduction of the electric double-layer condenser, as might otherwise be caused from the fact that the end portion of the electrode is spaced, at the two axial end portions of the laminated type polarized electrode, at the predetermined distance from that end portion, can be suppressed to a small value thereby to realize the polarized electrode for the electric double-layer condenser, with the aforementioned effects.
(3) In order to solve the aforementioned problems, according to the invention, there is provided a polarized electrode for a laminated type electric double-layer condenser, in which a band-shaped electrode member including an electrode: prepared by dispersing an active substance including mainly active carbon and a conductive filler through a binder and by forming them into a sheet shape; adhered to at least one face of a collecting foil having a conductivity; and cut to a desired size, and a separator having a shape corresponding to that of the electrode member are alternately laminated into a laminate. The end portion of the electrode is spaced, at the two axial end portions of the laminated type polarized electrode, at a distance of 0.1% or more of the width of the electrode member from the end portion of the electrode member.
With this construction, the end portion of the electrode is arranged, at the two axial end portions of the laminated type polarized electrode, at a distance of 0.1% or more of the width of the electrode member from the end portion of the electrode member. Therefore, the direct damage of the electrode can be prevented, even if a stress to act on the end portion of the polarized electrode occurs at the step of laminating the sheet-shaped polarized electrodes spirally through the dielectric separator having a shape corresponding to the polarized electrodes into the laminated member and at the step of packaging the laminated member. As a result, the separation of the end face of the electrode member and the falling of the active substance from the electrode member can be reduced to provide the polarized electrode for the laminated type electric double-layer condenser excellent in the voltage keeping characteristics.
(4) In the aforementioned polarized electrode for a laminated type electric double-layer condenser according to the invention, moreover, it is preferred that the end portion of the electrode is spaced at the two end portions of the laminated type polarized electrode, at a distance of 0.1% to 10% of the width of the electrode member from the end portion of the electrode member.
With this construction, there is embodied a polarized electrode, in which the capacity reduction of the electric double-layer condenser of the laminate, as might otherwise be caused from the fact that the end portion of the electrode is spaced, at the two end portions of the laminated type polarized electrode, at the predetermined distance from that end portion, can be suppressed to a smaller value.
Here in the invention, an electrode non-forming portion having no electrode is formed at the two end portions of the polarized electrode so that it may absorb and relax a stress, if any to act on the end portion of the polarized electrode. The stress on the polarized electrode portion can be eliminated to prevent the damage of the electrode more effectively.
If the aforementioned electrode non-forming portion is positioned between the end portion of a laminated type polarized electrode 1B or a laminated type polarized electrode 2B and the end portion of the electrode 1B or 2B which is arranged at a distance of 0.1% or more or preferably at a distance of 0.1% to 10% of the width of the electrode member from those end portions, the positioning can be suitably set according to the thickness, area or material of the collecting foil to be employed.
(5) Moreover, the invention provides an electric double-layer condenser comprising a polarized electrode for an electric double-layer condenser thus constructed.
With this construction, it is possible to realize the electric double-layer condenser, which is prevented from the problem that the manufacturing process is susceptible to the damage or separation of the polarized electrode, so that the yield can be improved to lower the cost and so that the desired performance can be exhibited stably for a long time.
The present invention is conceived to solve these problems and has an object to provide a polarized electrode for an electric double-layer condenser, which prevents the separation or falling of the electrode from the collecting foil, a process for manufacturing the polarized electrode, and an electric double-layer condenser manufactured by using that polarized electrode.
In view of the problems, we have made keen investigations and have found that the two end portions of the polarized electrode for the electric double-layer condenser and their peripheries have to be properly protected so as to prevent the separation or falling of the electrode from the collecting foil. Therefore, we have created the invention by finding the method, which can protect the two end portions of the electrode and their peripheries properly and easily when the electrode is to be adhered to the collecting foil.
(6) In order to solve the aforementioned problems, according to the invention, there is provided a polarized electrode for an electric double-layer condenser, in which an electrode prepared by dispersing an active substance including mainly active carbon and a conductive filler through a binder and by forming them into a sheet shape is adhered to at least one face of a collecting foil having a conductivity. The collecting foil has an etched portion subjected to an etching treatment, at the portion, to which the electrode is adhered, and in its vicinity. The etched portion is formed to have a width larger than that of the electrode and smaller than that of the adhesive layer. The adhesive layer has a width set larger by about 0.3 to 10% than that of the electrode member.
At this time, it is preferred that the central portion of the electrode is generally aligned with that of the adhesive layer.
With this construction, the adhesive layer formed on the collecting foil is wider than the electrode so that the two end portions of the electrode are coated with and protected by the adhesive layer when the collecting foil and the electrode are adhered through that adhesive layer.
(7) In the aforementioned polarized electrode for a laminated type electric double-layer condenser according to the invention, it is convenient that the adhesive layer is formed thicker at its two ends and their peripheries than at the remaining portions.
With this construction, the adhesive layer is formed thicker at its two ends and their peripheries than at the remaining portions. It is, therefore, possible to coat and protect the two end portions of the electrode and their peripheries sufficiently with the adhesive layer.
(8) In order to solve the aforementioned problems, according to the invention, there is provided a process for manufacturing an polarized electrode for an electric double-layer condenser according to the invention. The process comprises: the step of preparing an intimate mixture by kneading an active substance including mainly active carbon, a conductive filler and a binder; the step of preparing granules by pulverizing the intimate mixture;
the step of preparing an electrode by shaping the granules; the step of applying an adhesive to the etched portion, to which the electrode is to be adhered, of the collecting foil; and the step of manufacturing a polarized electrode by adhering the electrode to at least one face of the collecting foil through the adhesive applied at the adhesive applying step. The two ends of the adhesive layer formed at the adhesive applying step and their peripheries are made thicker than the remaining portions.
Thus, the two end portions of the adhesive layer and their peripheries are made thicker than the remaining portions. When the electrode is to be adhered to the collecting foil through the adhesive layer, therefore, the adhesive layer can be spread from the clearance between the electrode and the collecting foil to the two end portions of the electrode thereby to coat and protect the two end portions of the electrode and their peripheries sufficiently.
(9) The invention can use a mesh roll at the adhesive applying step of the process for manufacturing the polarized electrode for the electric double-layer condenser. At this time, more adhesive can be applied to the two widthwise ends of the mesh roll and their peripheries by making the mesh size larger at the two widthwise end portions of the mesh roll and their peripheries.
Thus, the adhesive layer can be made thicker at the two widthwise end portions of the etched portion of the collecting foil and their peripheries than at the remaining portions by passing the collecting foil through the mesh roll.
(10) Moreover, the invention can use a gravure roll at the adhesive applying step in the process for manufacturing the polarized electrode for the electric double-layer condenser. At this time, the gravure roll is provided with grooves to be filled with the adhesive in the roll face to be contacted by the collecting foil, and the adhesive-filled grooves are so deeper at the two widthwise ends of the roll face and their peripheries than at the remaining portions as to apply more adhesive at the two end portions and their peripheries.
Thus, the adhesive layer can be made thicker at the two widthwise end portions of the etched portion of the collecting foil and their peripheries than at the remaining portions by passing the collecting foil through the mesh roll.
Here, the mesh size of the mesh roll thus constructed or the grooves formed in the roll face of the gravure roll are suitably adjusted to the portion where the electrode is adhered to the collecting foil. If the application area of the adhesive to the collecting foil is made properly larger than the area of the portion, to which the electrode is adhered, for example, the effect obtained by making the two widthwise end portions of the collecting foil and their peripheries thicker than the remaining portions can be more improved to protect the two end portions of the electrode and their peripheries more sufficiently and properly.
(11) In order to solve the aforementioned problems, according to the invention, there is provided an electric double-layer condenser manufactured by using the aforementioned polarized electrode for the electric double-layer condenser.
With this construction, the two end portions of the electrode contained in the polarized electrode and their peripheries can be protected, and the adhesive properties between the electrode and the collecting foil can be further enhanced. It is, therefore, possible to provide an electric double-layer condense, which can have a strength for maintaining its shape while suppressing the cracking or breakage, even if used continuously for a long time in various modes and under various conditions, and which can coordinate sufficiently the flexibility and cost demanded for the shaping works at the manufacturing time.
Here, the invention can be applied to both the laminated type electric double-layer condenser and the laminated type electric double-layer condenser.
Still further, the invention is conceived in view of the situations thus far described and has an object to provide a process for manufacturing an electrode sheet for an electric double-layer condenser, by adhering sheet-shaped electrodes and a conductive foil through a conductive adhesive to give a sufficiently low contact resistance while retaining a sufficient joint strength. Another object of the invention is to provide a laminating apparatus suitable for executing the manufacturing process.
In order to manufacture a long electrode sheet for the electric double-layer condenser, we have investigated not only the material faces but also various experiments and researches, on the laminating step of adhering the sheet-shaped electrodes and the conductive foil through the conductive adhesive, how to reduce the contact resistance at the joint portion between the sheet-shaped electrodes and the conductive foil and how to retain the joint strength. As a result, we have developed an optimum adhering (or laminating) process using the conductive adhesive and conceived the invention.
Specifically, the process for manufacturing the electrode sheet for the electric double-layer condenser according to the invention of Aspect 12, is characterized in that the laminating step of adhering the long sheet-shaped electrodes to the surfaces of the long conductive foil through the conductive adhesive is done by adhering the sheet-shaped electrodes while applying the conductive adhesive with a thickness of 10 microns or less (which is measured after applied and dried) to the surfaces of the conductive foil by using a gravure coater.
According to this process, the gravure coater is engraved with mesh-shaped recesses in the surface of the application roll so that the conductive adhesive held in the surface is transferred for the application to the surfaces of the conductive foil. In this case, the conductive adhesive can be applied with a homogeneous and sufficiently small thickness (at 10 microns or less, preferably 0.1 to 5 microns) to the surfaces of the conductive foil while being held at a predetermined amount per unit area on the surface of the application roll. Moreover, the conductive particles in the conductive adhesive are transferred to migrate into the recesses of the application roll so that they are homogeneously applied without any deviation to the surfaces of the conductive foil thereby to provide excellent electric characteristics.
In the sheet-shaped electrodes and the conductive foil adhered through the conductive adhesive, therefore, according to the invention of Aspect 12, the thickness of the adhesive layer can be made homogenous and sufficiently thin to provide the excellent effects to reduce the contact resistance between the sheet-shaped electrodes and the conductive foil sufficiently and to retain a sufficient joint strength.
At this time, an aluminum foil or the like can be adopted as the aforementioned conductive foil. It is preferred that the adhered portions of the surfaces of the conductive foil are made rough in advance by an etching treatment or the like. By the resultant so-called xe2x80x9canchoring effectxe2x80x9d, the joint strength can be more enhanced, and the conductive particles (e.g., fine particles of graphite or carbon black) in the conductive adhesive migrated into the rough pores so that the electric characteristics can be further enhanced (to lower the contact resistance).
As the carbon powder of the shaping materials to be used for manufacturing the aforementioned sheet-shaped electrodes, on the other hand, there is mainly used the active carbon, which could be replaced by carbon nano-tubes or carbon fibers. The conductive assistant is mainly exemplified by carbon black, which could be replaced by fine particles of a highly conductive metal. As the binder, there can be adopted fluorineres in powder such as polytetrafluoroethylene (as will be abbreviated into the xe2x80x9cPTFExe2x80x9d).
At the time of preparing the aforementioned shaping materials, it is desired to mix and blend them in a proper ratio, to pulverize their intimate mixture and to pulverize it to a proper granular distribution. After this, the material can be made suitable for the preliminary shaping treatment by adding a proper amount of binder assistant and mixing them. As the binder assistant at this time, there can be adopted alcohols such as isopropyl alcohol (as will be abbreviated into xe2x80x9cIPAxe2x80x9d), ethers or ketones.
In order to prepare the long sheet-shaped electrodes, the aforementioned shaping materials are subjected to a calendering treatment, for example, to form the sheet-shaped component. After this, rolling treatments are done several times to prepare the long sheet-shaped electrodes of a desired thickness (e.g., 160 microns). By executing the slitting step as the last stage of the rolling step, the rolled sheet-shaped electrodes can be cut off at their two end edge portions to a predetermined width.
Here in the invention, the conductive adhesive is continuously applied thinly to the conductive foil. This may cause partially cuts (or an application failures) of the conductive adhesive, but the adhesion to the sheet-shaped electrodes is continuously done. Therefore, the application failure position of the adhesive may be difficult to specify. In the invention of Aspect 13, therefore, at the laminating step, the surface state of the conductive foil having the conductive adhesive applied thereto is continuously monitored by an image pickup device. Even if the adhesive is partially cut, for example, the proper treatment can be accordingly done after the adhesion by storing that failure position.
In a laminating apparatus of the invention of Aspect 14, moreover, the long sheet-shaped electrodes are adhered through the conductive adhesive to the surfaces of the long conductive foil thereby to manufacture the electrode sheet for the electric double-layer condenser. This laminating apparatus is provided with the adhesive applying section for applying the conductive adhesive with a thickness of 10 microns or less to the surfaces of the conductive foil by using a gravure coater. According to this construction, as described above, the thickness of the adhesive layer can be made homogenous and sufficiently thin to reduce the contact resistance between the sheet-shaped electrodes and the conductive foil sufficiently and to retain a sufficient joint strength, so that the aforementioned manufacturing process is properly executed.
According to the invention of Aspect 15, the aforementioned laminating apparatus of Aspect 14 comprises monitor section for continuously monitoring the surface state of the conductive foil having the conductive adhesive applied thereto, by an image pickup device. Even if the adhesive is partially cut, for example, the proper treatment can be accordingly done after the adhesion by storing that failure position.